Maggie- Another amp is born

[DougH]

Yes, the power supply is way overdesigned, I realize that. I had the 220's on hand and my obsessive "EE-ness" came out when I designed it. It was easy enough to get the ripple below 1v p-p so I went for it.

I originally left the .01u conjunctive filter cap off. But it was still a little "crispy" sounding when it was turned up. It really balanced it out for all three cabinets I tried it with. Yes, you should probably include a resistor at 1.25 * Zpri but this sounded good so I left it alone.

According to the datasheets I have, the 50L6 is a beam pentode.

I've seen a couple other diy-ed 50L6 amps where they use a 60v iso xformer for the heaters and double that for B+. Either way works but I thought this with the Pi filter etc would give it cleaner power.

I have the voltage measurements in my notes. I'm going to add those to the schematic.

[gtudoran]

Good job, Doug. Sounds very nice (if it sounds like the one from youtube video). Nice and simple schematic too. What is the primary impedance of the OT?

Best regards,
Gabriel Tudoran
Analog Sound

[Morocotopo]

Nice little amp Doug. Now, how about making an amp with NO controls?



Just use the ones on your guitar.

Anyone ever did that?

[DougH]

No reason you couldn't do that. For crunchy sounds I leave the vol all the way up so you could build it fixed that way if you'd like.

Gabriel, Zpri on this xformer is 3k, which is as low as it would go (3k/4k/5k Heyboer). Ideally it's supposed to be 2k, but it sounds fine like this. I think I put the load impedance on the schematic.

[DougH]

This still had some noise issues so I switched the heater circuit to DC. Now it is quiet as a mouse, seriously... It was a super-simple mod, just run the heater/resistor string from B+ to ground. Had to adjust the resistor a little higher. This amp is so quiet now it is ridiculous. Here's the updated schematic.

I have finished the head cabinet and I'll take some pics and do a demo video soon.